Was cruising around LS today and had a few more ideas to add to my wishlist...
1. The Casino and Racetrack should become functional as DLC, maybe with a Casino heist.
2. A Ballad of Gay Tony style set of club interiors, maybe with club management and other activities.
Want want want!

http://au.ign.com/wikis/gta-5/DLC
I WAS there last night, but they've since removed it. May not be true then.
You can still see some people discussing it via Google.
"i just saw this at ign. $49? so they know the price but dont give u one bit of info on what it is?"

And it's working! Intro has started up!
(5 minutes later...)
Hit another hiccup. I'm literally sitting in a game lobby waiting for the session to start. I was standing there by myself for a good 3 minutes before a few more players popped in. Still waiting for the session to start...
(10 minutes later)
Reloaded the session, and now I'm back waiting in a lobby.
Looks like I'm one of a million... http://support.rockstargames.com/hc/en-us/articles/200426246

From what Rockstar hinted at a while ago, I'm keen for a Liberty City expansion (with all the features and mechanics from V).
Also, I'm sure we'll get plenty of DLC missions too... Or maybe they'll just be free with the updates?